Known vitamin D compounds, such as cholecalciferol and dihydrotachysterol.sub.3 derivatives and metabolites thereof, promote both intestinal-calcium and phosphate transport and in conjunction with parathormone promote bone-calcium mobilization (bone resorbtion).
It is an object of the invention to find a class of novel cholecalciferol and dihydrotachysterol.sub.3 derivatives which promote intestinal-calcium transport without the usual magnitude of bone-calcium mobilization, i.e. selectively promote intestinal transport, expecially calcium, as opposed to bone mobilization. This differential effect has been widely sought for treatment of steroid-induced osteoporosis, senile osteoporosis and secondary hyperparathyroidism, especially that induced by an insufficient amount of calcium in relationship to the amount of phosphate.